Adherence to antiretroviral therapy is important to optimise treatment outcomes and prevent the development of drug resistance. It is however compromised under a number of situations in the countries most heavily affected by HIV/AIDS. The question we are concerned with is: 'How to keep people on treatment?' The answer lies in an understanding of why adherence is important; what levels of adherence are needed to ensure that treatment remains effective; how different types of crisis affect people's access to treatment; and how patients and service providers respond to such difficulties.

This paper considers the longer term impact of unplanned ART treatment interruptions and makes suggestions as to how they might be avoided and managed in future, based on a series of case studies. More specifically, it looks at problems with health system functioning and ART delivery during: 1) the 2007 public sector strike in South Africa, 2) the ongoing political and economic crisis in Zimbabwe, and 3) the 2008 floods in Mozambique. As the paper is a literature review, potential strategies identified in the final section of the review are limited in the sense that they are based on reports rather than original data. Nonetheless, we have not yet others taking a similar approach and our hope is that this synthesis will aid further research.